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RESULTS: Relative to Monday, Wednesdays, Thursdays, and Sundays were associated with a decreased likelihood of meeting MVPA recommendations. Wednesday thru Sunday were associated with a decreased likelihood of spending ≥55% of time sedentary. Being a boy, receiving transportation, and fewer reported barriers to physical activity were associated with meeting MVPA recommendations.

CONCLUSIONS: Sundays were associated with lower odds of meeting MVPA recommendations and spending ≥55% of time sedentary suggesting emphasis should be placed on activity intensity during this time. Supported by Robert Wood Johnson grant RWJ67126.

Clinically assessed gait speed is a valuable test of older adults’ functioning and an important predictor of adverse outcomes including disability, cognitive decline, falls, institutionalization, and mortality. It is logical to pursue correlates of gait speed.

RESULTS: Nearly all accelerometer-determined movement variables were significantly associated with gait speed, however, of all considered, steps/day had the strongest and most consistent relationship with gait speed (Spearman r = 0.562-0.578, partial r = 0.392-0.414, p < 0.001). There was evidence to suggest that the relationship (r=0.609) was stronger when focused on time spent at a cadence of 20+ steps/min compared to time spent at any cadence above zero (r=0.442). 1,100 steps/day and 2,200 steps/day were associated with 0.05 m/s and 0.1 m/s differences in gait speed, respectively. There was no relationship between time in sedentary behaviors and gait speed.

CONCLUSIONS: These cross-sectional data suggest that strategies to improve gait speed among older adults include walking more, and specifically replacing at least some of the abundant amount of time spent in sedentary behaviors and incidental movement with more purposeful ambulation.

231 Board #83 May 29, 9:30 AM - 11:00 AM

Seasonal Changes in Childcare-related Physical Activity and Sedentary Time Among Preschoolers

Results from several objective monitoring studies suggest that children’s physical activity (PA) patterns may change across seasons; however, it is not well understood how PA patterns in the childcare setting may change across seasons.

PURPOSE: To prospectively track preschoolers’ PA patterns during childcare while investigating for seasonal differences in accelerometer measured PA and sedentary (SED) time between the fall and winter months in Fargo, North Dakota.

METHODS: A total of 55 preschoolers (44% female) between the ages of 3 and 5 (mean age [M ± SE] = 4.3 ± 0.1 yrs) from 4 childcare centers wore an ActiGraph accelerometer (ActiTrainer; ActiGraph LLC, Penascola, FL) for 1 week in October/November 2011 (fall) and again in January/February 2012 (winter). Accelerometers were worn at all times while in the center other than naptime and time of arrival and departure was logged for each child daily. SED time, light PA (LPA), and moderate-to-vigorous PA (MVPA) during each assessment period was calculated and expressed relative to daily accelerometer wear time (min/hr). Repeated measures mixed model ANOVA was used to examine for changes in all PA variables from fall to winter with childcare center entered as a random effect in all models.

CONCLUSIONS: Preschoolers’ MVPA during childcare decreased by 2 min/hr (> 10 min/day) from fall to winter as SED time increased by 3.6 min/hr (≍ 19 min/day) during this period. Further research is needed to identify which factors are likely influencing these unfavorable seasonal changes in MVPA and SED time during childcare.

232 Board #84 May 29, 9:30 AM - 11:00 AM

Sedentary Behavior and Markers of Hepatic Lipid Load. The Cardiovascular Risk in Young Finns Study

PURPOSE: Sedentary behavior has been associated with increased risk of obesity, metabolic syndrome, type 2 diabetes, and cardiovascular disease, but the underlying pathogenic mechanisms are unknown. Hepatic lipid metabolism disturbances may lie behind many of these conditions, but the relationship of sedentary behavior and lipid overaccumulation has not been studied. We examined the association of TV hours and other leisure-time sedentary behavior (non-TV hours) with three established markers of hepatic lipid load: serum gamma-glutamyltransferase (GGT), the Lipid Accumulation Product (LAP) and the Fatty Liver Index (FLI).

METHODS: 1607 subjects (858 women, 749 men) aged 30-45 y were drawn from the population-based Cardiovascular Risk in Young Finns study. The LAP was calculated from waist circumference and fasting triglycerides. The FLI included waist circumference, fasting triglycerides, BMI and GGT. Data on leisure-time sedentary behavior (hours spent watching TV, using computer, reading, listening to music/radio, or other relaxation), physical activity (leisure-time and commuting to workplace), occupational physical strain, smoking, diet, energy intake and alcohol use were derived from questionnaires. The associations were studied with linear regression. Men and women were evaluated separately due to gender interactions seen for each marker.

RESULTS: Both TV and non-TV hours were directly associated with GGT, LAP and FLI when men and women were evaluated together (p <0.002, <0.02, <0.002 for TV and p<0.001, <0.03, and <0.0001 for non-TV hours, respectively). Adjustment for physical activity, occupational physical strain, energy and alcohol use, diet composition, smoking, age, and BMI did not change the results except that alcohol use diluted the association of non-TV hours with FLI in men (p=0.082), and TV hours with GGT in women (p<0.14) to statistically non-significant.

CONCLUSIONS: The associations of leisure-time sedentary behavior with hepatic lipid load indices in healthy adults suggest that sedentary lifestyle may be associated with fatty liver. Further studies including e.g. hepatic imaging are needed to test this hypothesis. Based on these findings, lipid overaccumulation may be one mechanism linking sedentary behavior with cardiometabolic disease risks.

233 Board #85 May 29, 9:30 AM - 11:00 AM

Body Mass Index Classification and No Self-Reported Physical Activity or Exercise in U.S. Adults

RESULTS: In 2009, the odds of no self-reported PA or exercise in underweight men and men in the class I, II and III obesity categories were 2.48 (95% CI 1.81-3.39), 1.38 (95% CI 1.26-1.50), 1.75 (95% CI 1.55-1.98), and 2.40 (95% CI 2.08-2.76), respectively, compared to men of desirable weight. Overweight men did not vary significantly (OR 0.96; 95% CI 0.89-1.04) from men of desirable weight. The odds of reporting no PA or exercise in underweight men were similar to class II and class III obese men. The odds of no PA or exercise in underweight women, overweight women, and women in the class I, II and III obesity categories were 1.67 (95% CI 1.44-1.95), 1.28 (95% CI 1.21-1.35), 1.71 (95% CI 1.61-1.82), 2.17 (95% CI 2.00-2.36), and 2.40 (95% CI 2.23-2.58), respectively, compared to women of desirable weight. The odds of reporting no PA or exercise were similar in underweight and class I obese women. Women were found to have greater odds of reporting no PA or exercise in three of the five non-desirable BMI categories (p<0.05) compared to men.

CONCLUSION: Within and between sex differences in the odds of reporting no PA or exercise vary significantly by BMI category.

234 Board #86 May 29, 9:30 AM - 11:00 AM

The Association Of Cardiovascular Indicators With Obesity, Physical Activity And Sedentary Activities In Children And Adolescents

RESULTS: The prevalence of metabolic syndrome according to Cook et al. (2003) criteria, was 4.8% and 25% had a very high %BF. With increasing age, there was also an increase in time spent in sedentary activity, and a decrease in levels of physical activity, cardiorespiratory fitness and a decline in the metabolic profile (p<.05). Girls had lower levels of physical activity and cardiorespiratory fitness (p<.05). Multiple linear regression analysis showed that the sum of skinfolds (both sexes) and sedentary behaviors (in boys), are significant predictors of metabolic risk factors (p<.05).

CONCLUSIONS: The development of programs for the prevention of cardiovascular diseases should target obesity and decreasing sedentary behaviors.

Sponsored by the Department of Education in Madeira Autonomous Region and Foundation for Science and Technology SFRH/BD/41642/2007.

235 Board #87 May 29, 9:30 AM - 11:00 AM

The Association Between Screen-based Sedentary Behavior And Lipid Profile Among Adolescents In Curitiba, ParanÁ, Brazil

Introduction: Over the past years technological advances and societal changes have increased sedentary behaviors among adolescents. As a result of this increase in time spent with low energy expenditure activities, such as watching TV and playing videogames or computer games, bad dietary and physical activity habits can be developed. Studies have demonstrated a connection between these habits, especially screen-based sedentary behavior, and the development of cardiovascular risk factors in children and adolescents, such as metabolic risk profile.

PURPOSE: The aim of this study was to analyze the association between screen-based sedentary behavior and lipid profile among a sample of adolescents in Curitiba, Paraná, Brazil.

METHODS: A cross-sectional school-based study was conducted on 573 adolescents (247 males) aged 12 to 17 from public schools in Curitiba, Paraná, Brazil. Total Cholesterol, LDL-cholesterol, HDL-cholesterol, and Triglycerides were measured. The time spent with screen-based activities was measured using the Adolescent Sedentary Activity Questionnaire, validated in Brazil (QASA). Physical activity level was verified by the IPAQ, and dietary intake was measured using a food frequency questionnaire. The study was approved by the ethics committee of Federal University of Paraná.

CONCLUSION: We conclude that screen-based sedentary behaviors are independently associated with total cholesterol and LDL-cholesterol levels. Prospective studies and interventions are needed to analyze the causality of these associations between screen-based sedentary behaviors and the risk of negative changes in lipid profile.

236 Board #88 May 29, 9:30 AM - 11:00 AM

Excessive Sedentary Behavior is Positively Associated with Changes in the BMI Frequency Distribution

Sedentary behavior has been associated with an increase in body mass index (BMI). However, past studies modeled the mean BMI or BMI categories and did not test if the association between sedentary behavior and BMI was uniform across the BMI frequency distribution. Further, reverse-causation is a concern of cross-sectional studies (higher BMI may predict higher sedentary behavior) and longitudinal studies are needed to support cross-sectional findings.

PURPOSE: To determine if sedentary behavior at baseline was cross-sectionally associated with BMI, and changes in BMI over 9 years, by modeling the median BMI and other percentiles of the BMI distribution.

METHODS: Participants were enrolled into the NIH-AARP Diet and Health study in 1995-1996 (median age 63). BMI was reported at baseline (n=272,152) and 9 years later (n=156,311). Overall sitting time was reported at baseline (<3 [referent], 3-4, 5-6, 7-8h or ≥9h/d), as were the covariates (age, sex, race, education, smoking, moderate-to-vigorous physical activity, calories, and sleep duration). Quantile regression was used to test for associations between sitting time and BMI at the 10th, 25th, 50th, 75th and 90th percentiles, adjusting for the covariates. The coefficients are interpreted in the same manner as linear regression coefficients.

CONCLUSION: Our findings provide evidence that adults engaging in more sedentary behavior had higher BMIs and gained more weight over time. The stronger associations at the upper tail of the BMI distribution mean that sitting less could shift the upper tail of the distribution to smaller BMI values and thereby reduce the prevalence of obesity at the population level.

A sedentary behavior (SB), typically involving prolonged periods of sitting, has been emerged as one of health risk factors. In addition, a manner of SB being accumulated during a day (e.g., prolonger vs. breakers) has also been reported as an independent predictor of health outcomes. However, little is known about the influence of bouts of prolonged SB on health outcomes.

PURPOSE: The purpose of this study was to investigate the influences of different bouts of prolonged SB on health outcomes.

METHODS: Data from the 2003 to 2004 National Health and Nutrition Examination Survey (NHANES) were analyzed. A total of 1385 adults (ages > 17 yr), who have valid measures of accelerometer data (defined as 4+ days with 10+ hr wear time) and components of metabolic syndrome, were included in the analysis. Activity counts less than 100 cpm were considered SB. An average minutes of SB (min-d) accumulated for different bout periods (i.e., 1-min, 5-min, 10-min, . . ., 30-min, and 60-min) per day and number of breaks (breaks-d) with respective to each bout period were obtained. SB outcomes were adjusted for wear time using residual method. Linear relationships between health outcomes and SB outcomes were examined after controlling for demographic characteristics. Complex sampling design in NHANES was taken account for all analyses.

RESULTS: Overall, an average minutes and number of breaks in 1-min bout of SB were 549.96 and 91.38, respectively. After considering the bout periods, times and number of breaks of SB were decreased as bout periods increased (e.g., 162.03 min-d and 26.81 breaks-d for 5-min bout period and 77.18 min-d and 12.74 breaks-d for 10-min bout period). After controlling for demographic characteristics,SB outcomes derived from 5-min and 10-min bout periods were shown to be better explanatory variables for components of metabolic syndrome.

CONCLUSSION: This study examined the influence of bout periods of SB on health outcomes using national representative sample of US adults. Using 5- or 10-min bout periods of SB would also be promising for better understanding of the relationships of SB and health outcomes.

238 Board #90 May 29, 9:30 AM - 11:00 AM

Examination Of Sedentary Time, Physical Activity, And Body Mass Index (BMI) In College-aged Students

PURPOSE: The purpose of this investigation compared physical activity levels, sedentary time, and BMI in college students who met and did not meet the 150 min/wk of moderate exercise recommendation.

METHODS: Data on n=619 students who completed the Student Health Assessment Project (SHAP), a cross-sectional survey of college student health was used for this investigation. Data was collected during the Spring 2011, Fall 2011, and Spring 2012 semesters. This survey consisted of questions related to safety and violence, tobacco, alcohol, and other drug use, diet, exercise, and sleep patterns, sexual behavior, stress, depression, and perceptions about body image. Subjects’ height and weight were measured to calculate BMI by researchers using a standard protocol in a private setting.

RESULTS: The mean age was 19.29+1.47 years, and included 64% females, and 93% Caucasians. According to BMI, 43% of the sample was classified as being overweight or obese with a BMI >25 kg/m2. When assessing physical activity, 64.5% of the subjects did not accumulate the recommended 150 min/wk of PA. It was reported that 12.31+5.04 hours per day was spent in sedentary behavior including napping, lying, sitting, and standing. All measures of physical activity were significantly higher (p<0.05) for those meeting the PA guidelines. There was no difference in BMI (p=.315), nor total sedentary time (p=.403) between the groups. There was not a relationship between moderate physical activity and total sedentary time (r=-.042, p>.05).

CONCLUSION: Although measures of physical activity were significantly different between those who met or did not meet physical activity guidelines, there was no difference in the sedentary behaviors between groups. Physical activity was not correlated with sedentary time. Therefore, when estimating health risk, sedentary activities such as sitting, lying down, napping, and standing should be measured independently in addition to the measurement of physical activity. Campus wide programming should not only target increasing physical activity but also specific strategies to reduce sedentary behaviors common on college campuses.

239 Board #91 May 29, 9:30 AM - 11:00 AM

Physical Activity, Sedentary Behavior and Blood Pressure in Young Adults

Sedentary behavior (SED) is associated with an increased risk of cardiovascular disease (CVD) morbidity and mortality. Although physical activity (PA) is associated with a decrease in CVD risk, PA may not be able to mitigate CVD risk associated with excessive SED. Separation of blood pressure (BP) waves into its constituent forward wave pressure (Pf) and backward wave pressure (Pb) can provide insight into CVD risk as elevated Pf and Pb are associated with increased CVD morbidity and mortality.

PURPOSE: To examine the associations of PA and SED with novel measures of CVD risk (Pf and Pb).

METHODS: Aortic pressure waveforms were obtained using radial applanation tonometry and a generalized transfer function in 44 young healthy men (n = 26) and women (age 25± 1 yrs, BMI 24±1 kg/m2). A wave separation technique utilizing aortic flow triangulation was used to derive Pf (pressure due to the interaction of left ventricular contraction and aortic impedance) and Pb (pressure attributable to wave reflections). Levels of PA (METS/week) and SED (sitting time/day) were obtained via self-report using the International Physical Activity Questionnaire (IPAQ).

CONCLUSIONS: Time spent in SED behavior is associated with higher Pf and Pb. Adjusting for PA does not alter this relationship suggesting that young adults should be encouraged to reduce time spent in SED behavior to fully realize the favorable BP effects of PA.

240 Board #92 May 29, 9:30 AM - 11:00 AM

Effect of Sedentary Time on Physical Fitness in Overweight and Obese Adults

RESULTS: SED time was greater on weekdays vs. weekends (p<0.001), but only weekend SED time was correlated with GXT duration. Though subjects were inactive by study inclusion criteria, MVPA was marginally associated with GXT duration. These associations persisted in partial correlations with weekend SED and MVPA, suggesting independent effects on fitness (Table). Overall and weekday SED time were not related to GXT duration.

CONCLUSIONS: SED time was greater on weekdays, but only weekend time was related to fitness with and without adjustment for MVPA. These data suggest that interventions could target decreasing weekend SED time, along with increasing physical activity, to improve fitness.

16-40% (self-report and objective measures) of adults with knee osteoarthritis (OA) reportedly meet physical activity (PA) guidelines and a large proportion are classified as inactive (Dunlop et al., 2011). In these studies inactivity is considered the lack of moderate-to-vigorous PA (MVPA). However, sedentary behavior (SB) should be examined as SB has been linked to health outcomes, independent of MVPA. In addition, as OA progresses, the pattern of change in PA and SB is unknown.

METHODS: Patients with moderate/severe knee and hip OA (mean WOMAC= 32.8+16.91) seeking care at one specialty clinic were invited to participate. Data on the initial 14 of 45 participants (mean age=57.0+7.46 years; BMI=35.2+ 8.28 kg/m2) who wore an activPAL (AP) monitor for 7-days at baseline, 3, 6, and 9 months were analyzed. SB was computed from the AP as a % of monitor wear time spent sedentary (%SED). Activity variables included: % of wear time standing (%STAND), % of wear time stepping (%STEP), steps per day, stepping rate per minute (STEP RATE), and minutes of MVPA. Linear mixed effect models were used to test for differences at 3,6, and 9 months compared to baseline. 95% confidence intervals were used to identify significance.

Physical activity can benefit the health of youth with Type 1 diabetes. Despite the benefits some studies have found patients do not always meet the physical activity recommendation of 60 minutes of moderate-to-vigorous physical activity (MVPA) per day. Physical activity and sedentary behaviour have not been measured previously in Scottish youth with Type 1 diabetes.

METHODS: Twenty children (9M/11F) aged 7-9yrs and 20 adolescents (11M/9F) aged 12-14yrs with Type 1 diabetes were recruited from a clinic in Glasgow. Participants wore the Actigraph GT3X+ accelerometer for 7 days during all waking hours except during water-based activities. Participants with ≥10 hours of data (between 06:00-23.59 hours) over 3 days were included in analysis. Data were downloaded in 15-s epochs. Time in MVPA (≥3200cpm) and sedentary behaviour (<800cpm) were determined using validated and calibrated cut-points for youth (Puyau, et al., 2002).

RESULTS: All participants had sufficient data to be included in analysis. Participants spent (mean±SD) 208±118 minutes/week in MVPA and 3932±144 minutes/week in sedentary behaviour. Average daily MVPA was 33±3 minutes/day and sedentary time was 644±13 minutes/day. No participants achieved 60 minutes MVPA every day that they wore the monitor and 23/40 (56%) participants did not meet the guidelines on any wear day.

CONCLUSION: None of the participants met the minimum guideline for physical activity on every day of monitor wear. However, participants were not any less active than healthy youth of similar ages in UK studies using similar data collection and handling techniques. An average of 81% of each day was spent in sedentary behaviour. Given the importance of physical activity in the management of Type 1 diabetes this study confirms the need for physical activity and sedentary behaviour interventions in Scottish youth with Type 1 diabetes.

243 Board #95 May 29, 9:30 AM - 11:00 AM

Role of Sedentary Behaviour and Moderate-to-Vigorous Physical Activity on Fatness Phenotypes in Children

Sedentary behaviour (SB), which is characterized by the absence or low physical movement (e.g. sitting or watching TV) and by low energy expenditure (≤1.5 METs), has been associated with detrimental health effects, such as body fatness.

PURPOSE: To examine the bi-directional associations between objective measures of SB and moderate-to-vigorous physical activity (MVPA) with total body fat (TBF) and abdominal body fat (ABF) in 10 to 11 year-old children.

RESULTS: SB revealed to be independently associated with TBF (β=0.161, p=0.004) and ABF (β=0.151, p=0.007), after adjustment for age, gender, and register time of the accelerometer. However, after including MVPA in the model, the associations between SB and TBF (β=0.082, p=0.266) and ABF (β=0.056, p=0.449) were no longer significant. The only variable that remained statistically significant in the model was MVPA, but only in the ABF analysis (β=-0.007, p=0.046). Considering the opposite analysis of associations, the results remained similar with TBF (β=0.153, p=0.004) and ABF (β=0.144, p=0.007) being independently associated with SB. Nevertheless, after introducing MVPA into the model, the associations between these variables were once again non-significant (β=0.046, p=0.266 and β=0.031, p=0.449 for TBF and ABF, respectively).

CONCLUSION: Associations of SB and phenotypes of fatness such as TBF and ABF were bi-directional. Regardless of the direction of these relationships, the results highlight the importance of decreasing SB, and increasing MVPA especially in order to improve the ABF phenotype in boys and girls 10 to 11 year-old.

244 Board #96 May 29, 9:30 AM - 11:00 AM

Male Perceptions of Physical Activity and Sedentary Behavior in a University Work Environment

Promoting physical activity (PA) and reducing sedentary behavior (SB) in males can be challenging, and interventions tailored specifically for males are limited. As evidence emerges on the independent risk of chronic disease from both PA and SB, understanding male perceptions of PA and SB is important to inform development of relevant interventions, especially for males who work in an office setting.

PURPOSE: The purpose of this study was to explore male university employees’ perceptions on a range of issues related to participation in PA and SB.

METHODS: A purposive sampling strategy was used to recruit male employees in an Australian university aged 35-64 years, to partake in a focus group. Five focus group sessions were conducted on two campuses at the University of Western Sydney, with a total of 15 participants. The number of participants in the focus groups ranged from two to four, and sessions ran for approximately 60 minutes. The mean (±SD) age of participants was 46.1 (±8.0y), and academic staff accounted for 60% of the sample. Topics for discussion included benefits, barriers, enablers, and motivators for PA, and daily SB.

RESULTS: Participants were aware of the many benefits associated with regular PA, including improved health and reduced risk of chronic disease. Despite this, some participants revealed that being aware of the benefits was not enough to encourage a lifestyle change. Health and family were two of the most commonly discussed motivators for PA, whereas time constraints and work commitments were two of the major barriers to PA. Many saw inactivity as a “by-product” of their university employment, as a substantial proportion of their days were spent sitting, primarily at a computer, for work-related tasks. Participants reported that PA during working hours needed be recognized as a legitimate activity embedded within the university culture and endorsed using a top-down approach.

CONCLUSION: Participants’ motivation for, and awareness of the benefits of regular PA was not enough to overcome their perceived barriers. Considering the amount of time employees spend at work, it is important to recognize PA as a legitimate activity that is supported and encouraged during working hours. These findings can be used as a platform from which to develop targeted strategies to promote PA in male university employees.

PURPOSE: To describe the physical activity levels and sedentary behavior of toddlers from Ventura County, California

METHODS:Physical activity and sedentary behavior was measured in twenty three- (10 boys, 13 girls) toddlers (n= 22 toddlers, mean age 1.65 ± 0.49) using the Actigraph GT1M (Pensacola, Florida). GT1m’s were worn for a minimum of 6 waking hours per day (approximately 60% of the waking hours for children of this age), for a minimum of 4 days. Age appropriate cut-offs were used to categorize intensities of physical activity and describe levels of sedentary behavior.

RESULTS:Toddlers spent a total of 3190 ±1217.2 minutes per week engaged in total physical activity. Time spent in sedentary behaviors was 55.2 ± 6.0% for males and 56.8 ±6.5% for females. The gender difference was not statistically significant (ANOVA, p=0.55). Boys spent 1.36 ± 0.22% and girls 1.52 ± 0.11% of their time at light intensity physical activity, with a trend for gender difference significance, (ANOVA, p=0.06). The gender difference for time spent at moderate to vigorous physical activity was not statistically significant (Males 43.5 ± 6.0; Females 41.7 ± 6.5; ANOVA, p=0.51).

CONCLUSIONS:While preschoolers spent the majority of their day sedentary, our toddlers spent a considerable amount of the day at either sedentary behavior or engaged in MVPA. Future studies should investigate the transition from toddler to preschooler and its implications on physical activity.

246 Board #98 May 29, 9:30 AM - 11:00 AM

The Objective Association Between Sedentary Behavior and Physical Activity for Children Aged 6-12 Years

Children’s sedentary behavior (SB) has recently received increasing attention. SB has typically been measured by self-reported TV viewing or other screen time. Meta-analysis revealed the self-reported association between SB and physical activity (PA) to be small. However, limited objective studies have been conducted to examine the relationship between SB and PA.

PURPOSE: To examine the association between SB and PA using objectively measured accelerometer data.

METHODS: Observations from wrist-mounted accelerometers were collected for 269 1st, 3rd, and 5th grade students (49.1% female; mean age=8.7, SD=1.8 years) randomly selected from 4 Denver, CO, schools in spring 2010. An epoch length of 15 seconds was recorded from 6:00 am to 11:00 pm on 4-6 consecutive days (including 2 weekend days). Measured SB time and moderate to vigorous PA (MVPA) time were calculated (average hours per weekday * 5 + average hours per weekend * 2)/7). Correlations were calculated between SB and MVPA time for the whole sample and separately by gender and grade with Bonferonni corrected significance set a priori at <0.05/6 <0.0083.

CONCLUSION: Using objectively measured data, SB was significantly negatively associated with MVPA, where the extent of association was much stronger than many traditional self-reported results. This suggests that decreasing SB may have the additional positive effect of increasing PA for children and vice versa potentially increasing the impact of interventions addressing these behaviors.